Lasers are used in many firearms applications as tools to enhance targeting. For example, one form of firearm sight makes use of a laser placed on a handgun or a rifle and aligned to emit a beam parallel to the barrel. Since a laser beam by definition has low divergence, the laser light appears as a small spot even at long distances. The user places the spot on the desired target and the barrel of the gun is aligned (but not necessarily allowing for bullet drop or movement of the target while the bullet travels). Most laser sights use a red or green laser diode. Others use an infrared (IR) diode to produce a dot invisible to the naked human eye but detectable with night vision devices.
Lighting devices also may be used with firearms in order to illuminate the field or stun the target. Such lighting devices may include visible (e.g., white) lights and/or infrared lights, for instance for use in low lighting conditions with night vision goggles. However, laser sights and illumination devices can be bulky and awkward to use, and can render the firearm incompatible with a holster. They can also be difficult to mount on the firearm, and can be expensive.